Rivet Element Axial Insertion and Deformation
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Solution Overview
Problem
Existing rivet fastening methods are time-consuming and require complex devices due to the need for rotary motions and internal threads, leading to prolonged cycle times and undesirable noise from mandrel retention in blind rivets.
Innovation Solution
A method using a one-piece rivet element with a hollow shank, closed punch head, and flange, where a mandrel is used only for axial insertion to form a rivet hole and then withdrawn, allowing a riveting die to deform the rivet element into a closure flange without transmitting tensile force, thus eliminating the need for internal threads and reducing production complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If internal threads are used in the rivet element bore for mandrel connection, then the mandrel can be securely retained during setting, but the cycle time increases due to screwing and unscrewing operations
Solution Approach 1:
The invention extracts the threading function from the rivet element by using a separate threaded insert component that is inserted into the bore after the rivet is set. This allows the mandrel to be retained during setting without requiring the rivet element itself to have internal threads, thereby reducing cycle time while maintaining reliability.
Solution Approach 2:
The connection system is segmented into separate components: the rivet element with a smooth bore, the threaded insert, and the mandrel. This segmentation allows each component to perform its specific function optimally - the rivet element for fastening, the threaded insert for mandrel retention, and the mandrel for setting operation.
2Strength
If internal threads are provided in the rivet element, then the mandrel can be connected for force transmission, but the device complexity increases due to requirements for rotary motions in addition to axial motions
Solution Approach 1:
The rotary motion function is extracted from the fastening device by using a separate threaded insert that remains in the rivet element after setting. The mandrel only requires axial motion for setting, while the threaded insert provides the rotary connection interface separately, simplifying the fastening device structure.
Solution Approach 2:
Instead of providing threads in the rivet element bore and requiring the mandrel to screw in, the invention inverts the approach by using a threaded insert that is inserted into the bore after setting. This inversion eliminates the need for complex rotary mechanisms during the fastening operation.
3Strength
If the rivet element has a long thread section for force transmission, then the mandrel connection is secure, but the rivet element has a relatively long projecting length on the back of the workpiece
Solution Approach 1:
The force transmission function is segmented from the rivet element body and transferred to the separate threaded insert. This allows the rivet element to have a short, clean profile while the threaded insert provides the necessary thread engagement length for secure mandrel connection without increasing the rivet element's projecting length.
Solution Approach 2:
The thread section is extracted from the rivet element and placed in a separate insert component. This extraction allows the rivet element to maintain a compact design with minimal projecting length while the threaded insert provides sufficient thread engagement for strong force transmission.
4Reliability
If a blind rivet with mandrel head retention is used, then the mandrel can be accommodated in the rivet body, but undesirable rattling noises occur if the mandrel head is not clamped firmly
Solution Approach 1:
The mandrel head retention function is extracted from the rivet body by using a separate threaded insert. The mandrel head rests on the insert rather than being retained within the rivet body, eliminating the rattling noise issue while maintaining secure accommodation. The insert provides a dedicated interface that firmly clamps the mandrel head in place.
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
This method significantly reduces cycle time, minimizes production costs, and prevents rattling noises by eliminating the need for internal threads and mandrel retention, while allowing for a compact rivet design and enhanced water-tightness.
Implementation Method 1
inserting a mandrel into the bore of the rivet element by an axial motion until the mandrel end contacts the punch head, pressing the punch head against the at least one supported workpiece by means of a force acting on the mandrel
Implementation Method 2
placing a riveting die on the punch head and deforming the deformation region of the shank into a closure flange that contacts the workpiece
Data Source
Figure 1~2e
Figure 3
AI summary
In a method for fastening a rivet element (1) to at least one workpiece (W) a rivet element (1) is used that has has a hollow shank (2), a punch head (5) at one end of the shank (2), a flange (8) at a distance from the punch head (5), and a deformation region (9) between the flange (8) and the punch head (5). By means of a cylindrical mandrel (15) of a fastening device (20), the punch head (5) of the rivet element (1) is pressed through the workpiece supported on a first dolly (12), thereby forming a rivet hole. Subsequently, by means of a riveting die (17) directed toward the punch head (5), the deformation region (9) of the shank (2) is formed into a closure flange (18) contacting the workpiece (W), wherein the flange of the rivet element (1) is supported on a second dolly (14).