SPR Collet Slot Structure for Short Rivet Orientation Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional collets for self-piercing rivets (SPRs) fail to securely fasten short SPRs, leading to inversion and tearing due to a large gap between sheets and expansion load on O-rings, making it difficult to notice O-ring breakage and resulting in ineffective rivet holding.
Innovation Solution
A rivet fastening device with a cylindrical design featuring an inlet unit, first and second feeding units, and an outlet unit, equipped with strategically placed slots and varying wall thicknesses to prevent inversion and reduce tearing, eliminating the need for an O-ring by applying appropriate tension and maintaining the SPR's direction throughout the feeding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional collet with O-ring is used to feed SPR, then the structure is simple and easy to manufacture, but the O-ring tears and breaks due to expansion load, causing the rivet to be inverted
Solution Approach 1:
The invention removes the O-ring component entirely from the collet structure. The collet is designed as a rubber-elastic cylindrical body with internal grooves that directly guide the rivet, eliminating the need for an O-ring to maintain sealing or guiding function. This extraction of the problematic O-ring component resolves the reliability issue while maintaining manufacturing simplicity.
Solution Approach 2:
The invention replaces the durable but problematic O-ring with a disposable rivet guide structure integrated into the collet. The guide portion is designed to be replaced or the entire collet is designed as a single-use component that ensures reliable rivet guidance without relying on elastic O-rings that degrade under expansion loads.
2Length of moving object
If the collet is tapered to create space for inversion, then short SPR can pass through, but the rivet cannot be held securely and inversion occurs
Solution Approach 1:
The collet is segmented into distinct functional zones: an inlet portion, a guiding portion with internal grooves, and an outlet portion. The guiding portion contains multiple grooves that actively hold and guide the rivet shaft, preventing inversion while accommodating short SPR. This segmentation allows different portions to perform specialized functions rather than relying on a simple tapered shape.
Solution Approach 2:
The internal grooves in the collet act as an intermediary structure between the rivet and the collet walls. These grooves provide positive engagement with the rivet shaft, preventing inversion while allowing the rivet to pass through. The grooves serve as a mechanical mediator that transfers and controls the rivet's movement without requiring the rivet to be held by friction alone.
3Manufacturing precision
If the O-ring extends to the rivet flange diameter, then the rivet can be guided, but the O-ring is torn and broken due to expansion load
Solution Approach 1:
The invention removes the O-ring component entirely and replaces it with integrated guiding grooves formed directly in the collet body. These grooves provide the necessary guidance function without requiring an separate elastic element that is susceptible to tearing under expansion loads.
Solution Approach 2:
The collet is made of rubber-elastic material that provides both structural support and guiding function through its molded grooves. This composite approach integrates the guiding function into the collet body itself, eliminating the need for a separate O-ring component and reducing the number of parts that can fail.
Data Source
AI summary
A collet to feed and fasten cylindrical rivets includes an inlet unit that accepts and supports the rivet, a first feeding unit connected from the inlet unit and configured to feed the rivet, a second feeding unit connected to the first feeding unit opposite to the inlet unit and configured to feed the rivet, and an outlet unit that is connected to the second feeding unit opposite to the first feeding unit and supports the rivet that is fed to it. The inlet unit and the first feeding unit have at least two first slots at opposite angles, the second feeding unit and the outlet unit have more of second slots than the first slots, and when the rivet enters the first feeding unit, the second slots are closed by the opening of the first slots.