Blind Rivet Stem Locking Structure Against Recoil
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Solution Overview
Problem
Blind rivets, particularly break-stem types, face issues with relative movement between the body and stem post-setting, leading to reduced fastening strength due to recoil or vibration, especially in large workpieces with high tensile strength stems.
Innovation Solution
A rivet design featuring a body and stem with locking features, where the head displaces relative to the shank to engage with the stem, utilizing a stem locking feature and a body locking feature to securely lock the stem in place, enhancing the fastening strength and preventing recoil.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a break-stem rivet is used to fasten workpiece members, then the fastening operation can be completed from one side (blind side), but the stem may recoil and move relative to the body after setting, reducing fastening strength
Solution Approach 1:
The patent applies preliminary anti-action by incorporating a locking mechanism that prevents the stem from recoiling or moving relative to the body after setting. The locking feature creates a mechanical interlock that counteracts the natural tendency of the stem to move, thereby maintaining fastening strength while preserving blind side installation capability.
Solution Approach 2:
The patent segments the stem and body with distinct locking features - a locking feature on the stem and a corresponding locking feature in the body bore. This segmentation allows each component to have a specific function while working together to prevent relative movement, resolving the contradiction between ease of operation and reliability.
2Reliability
If conventional locking features are added to prevent stem recoil, then fastening strength is improved, but the device complexity increases
Solution Approach 1:
The patent applies local quality by adding locking features only at specific locations - a locking feature on the stem and a corresponding locking feature in the body bore - rather than redesigning the entire rivet structure. This localized approach improves reliability while minimizing increases in device complexity.
Solution Approach 2:
The locking feature on the stem fits into the locking feature in the body bore, creating a nested structure. This nesting approach allows the locking mechanism to be integrated within the existing rivet geometry, improving fastening strength without significantly increasing overall device complexity.
3Strength
If the stem is made of high tensile strength material to handle large workpieces, then the fastening capacity is improved, but the stem becomes more prone to recoil
Solution Approach 1:
The patent applies preliminary anti-action by incorporating a locking mechanism that prevents the high-strength stem from recoiling after setting. The locking feature creates a mechanical interlock that counteracts the elastic recovery tendency of high-strength stem materials, allowing the use of high-tensile-strength materials for large workpiece applications without compromising stem stability.
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 provides a robust lock that improves the shear and tensile strength of the fastening, preventing stem recoil and vibration-induced loosening, while being simpler to manufacture and applicable to larger workpieces.
Implementation Method 1
the head of the body of the rivet undergoes displacement relative to the shank to engage with the stem to lock the stem in place relative to the body and/or the workpiece members
Implementation Method 2
an enlarged portion arranged for radially expanding the shank when the enlarged portion is forced into said bore to fasten the workpiece members
Data Source
AI summary
A rivet for fastening workpiece members, the rivet including a body comprising a shank extending in a first, longitudinal direction and a head extending in a second, substantially transversal direction, a bore being defined through the shank and the head of the body; and, a stem comprising a main longitudinal portion arranged for insertion into said bore, and an enlarged portion arranged for radially expanding the shank when the enlarged portion is forced into said bore to fasten the workpiece members; the rivet being configured for insertion into respective apertures formed in the workpiece members; and the rivet being further configured such that when the workpiece members are fastened, the head of the body of the rivet is displaced relative to the shank to engage with the stem to lock the stem in place relative to the body and/or the workpiece members.