Blind Rivet Mandrel Breaking Groove Geometry for Clamping Force
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Solution Overview
Problem
Conventional blind rivets with a single-piece sleeve face limitations in clamping force due to deformation of crimping grooves during traction, leading to poor clamping and centering issues, and require a breaking groove that compromises the deformation of the sleeve.
Innovation Solution
A blind rivet design featuring a hollow sleeve with a mandrel having a progressive breaking groove, preformed crimping grooves extending beyond the sleeve, embrittlement grooves, and an added crimping ring, which directs deformation to prevent crimping groove deformation and ensures full clamping force, using materials with different deformation properties for the bulb and body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a breaking groove is provided in the mandrel to allow breaking off, then the mandrel can be broken off when traction load reaches a certain value, but the grooves deform during transmission of traction load resulting in poor crimping and poor clamping
Solution Approach 1:
The mandrel is pre-formed with crimping grooves that extend beyond the sleeve before installation. This preliminary positioning ensures that when the mandrel breaks at the breaking groove, the crimping grooves are already in the correct position to receive the crimping ring, preventing deformation during the breaking process and ensuring proper crimping quality.
Solution Approach 2:
The mandrel is segmented into different functional zones: a breaking groove zone that allows controlled fracture, and crimping groove zones that extend beyond the sleeve to maintain structural integrity during breaking. This segmentation allows the breaking groove to fulfill its function while the crimping grooves remain undeformed and effective.
2Force
If the breaking groove is enlarged to allow breaking off before deformation of crimping grooves, then breaking occurs earlier, but the inserting cannot be good since the total deformation of the sleeve cannot be guaranteed
Solution Approach 1:
The crimping grooves are pre-formed to extend beyond the sleeve length, establishing a reference structure before the breaking operation. This allows the breaking groove to be positioned and sized optimally for early breaking without compromising sleeve deformation, as the extended crimping grooves will naturally guide the breaking process and ensure complete sleeve deformation.
3Device complexity
If a single-piece sleeve is used, then the structure is simple, but the sleeve deforms under axial load causing crimping grooves to deform and reducing clamping effectiveness
Solution Approach 1:
The solution segments the functional zones of the single-piece sleeve by pre-forming crimping grooves that extend beyond the sleeve body. This creates distinct deformation zones: the sleeve body deforms to provide clamping, while the extended crimping grooves remain structurally stable to receive the crimping ring effectively, maintaining both simplicity and clamping force.
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 provides optimized mechanical performance with enhanced clamping, traction, and shear resistance, ensuring effective fixing comparable to screwed connections while maintaining crimping groove integrity and adaptability to various materials.
Implementation Method 1
a shank to which clutches a tool to imprint upon it a traction load
Implementation Method 2
the sleeve is preformed in order to deform under the axial load in such a way that a portion of the sleeve is urged to be opened around the portion of the sleeve remaining fixed
Implementation Method 3
an added crimping ring that is urged to crimp on the crimping grooves extending beyond the sleeve
Data Source
AI summary
Disclosed is blind rivet including a hollow sleeve, a crimping ring, and a mandrel, received by the hollow sleeve and by the crimping ring. The mandrel includes a head configured to bear against the sleeve, and a shank configured to receive a traction load from a tool. There is a breaking groove which breaks off when the traction load reaches a certain value. The breaking groove including a breaking groove bottom, a first breaking-groove-side extending from the breaking groove bottom toward the shank, a second breaking-groove-side extending from the breaking groove bottom towards the head. A first breaking-groove-side and a central axis of the mandrel define a first angle, and a second breaking-groove-side and the central axis define an angle greater than the first angle. An embrittlement groove is contiguous with the first breaking-groove-side.