Blind Rivet Plastic Body Mandrel Segmentation
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Solution Overview
Problem
Existing blind rivets are difficult to remove and require significant force for installation, leading to potential damage during disassembly, especially in applications like the automotive industry, where they are used for joining parts like door module supports.
Innovation Solution
A blind rivet with a hollow plastic body and a mandrel system that forms an annular bead upon deformation, allowing for strong axial contact pressure and easy removal by reversing the mandrel, reducing material stress and enabling single-piece extraction without damaging surrounding components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a blind rivet with hard mandrel material (e.g., steel) is used, then the rivet provides strong joining force, but the drill wanders during removal causing damage to surrounding components
Solution Approach 1:
The mandrel is segmented into a hard portion (for maintaining joining force) and a soft portion (for easy removal). The soft portion extends beyond the hard portion and is specifically designed to be removed without damaging surrounding components, while the hard portion remains to maintain the structural integrity and joining strength of the rivet.
Solution Approach 2:
Different portions of the mandrel have different material properties: the inner portion is made of hard material (steel) to provide strong joining force, while the outer portion extending beyond is made of soft material (aluminum) to enable easy removal without drill wandering. This local differentiation of material properties resolves the contradiction between strength and ease of removal.
2Ease of operation
If a blind rivet with soft mandrel material (e.g., aluminum) is used, then the rivet can be easily removed, but the joining force is insufficient
Solution Approach 1:
The mandrel is divided into functional segments: a hard inner portion for maintaining joining strength and a soft outer portion for easy removal. This segmentation allows each portion to fulfill its specific function optimally without compromising the other.
Solution Approach 2:
The mandrel exhibits local quality variation with hard material at the core for strength and soft material at the periphery for ease of removal, resolving the contradiction between joining force and removal ease.
3Strength
If high forces are applied during blind rivet installation, then the rivet achieves strong joining, but surrounding components may be damaged
Solution Approach 1:
The mandrel's material parameters are changed along its length, with the soft outer portion allowing for lower installation forces while the hard inner portion ensures sufficient joining strength is achieved. This parameter gradient reduces the peak forces required during installation.
4Ease of repair
If a blind rivet is designed for easy removal, then repair work is simplified, but the holding forces during service are reduced
Solution Approach 1:
The mandrel is segmented into a load-bearing hard portion that maintains holding forces during service and a removable soft portion that enables easy extraction during repair. The soft portion is specifically designed to be the first to fail during removal, simplifying the repair process.
Solution Approach 2:
Different portions of the mandrel have different material properties optimized for different phases: hard material for service (holding force) and soft material for repair (easy removal).
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 blind rivet achieves reliable and durable joining with minimal installation force, provides a seal that is not affected by hole edge damage or eccentric positioning, and can be easily removed for repair, maintaining clamping force under vibratory loads and temperature changes.
Implementation Method 1
the wall of the section of the first region located between the foot end and the second region forms a roll fold that on the outside rests against the section located between the head and the second region, and forms an annular bead pressed against the workpiece
Implementation Method 2
a mandrel head that stands in operative connection with the foot end of the rivet body in order to transmit a force to the rivet body during setting of the blind rivet
Implementation Method 3
The blind rivet can be made of an elastic plastic material and, in the fastened state, can maintain its clamping force even under the action of vibratory loads or temperature changes
Data Source
Figure 1~2
Figure 3
AI summary
In a blind rivet (10) having a hollow rivet body (11) made of plastic, having an elongated shank (13) with a bore (14), having a head (15) at one end of the shank and a foot end (19) on the opposite end of the shank (13), and having, located in the bore (14), a mandrel (12) that has a mandrel shank with a drawing end (38) and a mandrel head (35) that acts on the foot end (19), the shank (13) has a first region (21) with reduced cross-section and reduced wall thickness located between the head (15) and the foot end (19), and has, within the first region (21), a second region (22) with reduced cross-section and reduced wall thickness as compared to the first region (21). The regions (21, 22) are arranged such that, as a result of a process in which the head (15) is pressed against one side of a workpiece and the foot end (19) is simultaneously drawn toward the other side of the workpiece with the aid of the mandrel (12), the wall of the shank (13) forms a roll fold with an annular bead that is pressed against the other side of the workpiece.