Joining Die Polylobular Aperture for Offset-Safe Anchoring
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Solution Overview
Problem
Existing devices for inserting auxiliary joining parts into workpieces often suffer from center offset issues, leading to insecure anchoring of the auxiliary joining part in the workpiece, particularly in series manufacturing.
Innovation Solution
The device incorporates a die with a polylobular aperture periphery, where the periphery's outermost and innermost points lie on imaginary circumscribed and inscribed circles, respectively, and features at least three projections protruding into the circumscribed circle that touch the inscribed circle, optimizing the overlap area with the auxiliary joining part even with center offsets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a circular aperture in the die is used to receive the auxiliary joining part, then the auxiliary joining part can be inserted, but center offset occurs between the auxiliary joining part and the die leading to insecure anchoring
Solution Approach 1:
The patent applies asymmetry by changing the aperture shape from circular to polylobular (e.g., three-lobed or four-lobed configuration). This asymmetric geometry creates multiple contact zones between the circular auxiliary joining part and the aperture periphery, ensuring that even with center offset, the auxiliary joining part maintains sufficient overlap and anchoring security. The asymmetric lobes distribute the contact forces more effectively across the interface.
Solution Approach 2:
The patent changes the geometric parameters of the aperture by defining specific relationships between the circumscribed circle (passing through outermost points of lobes) and inscribed circle (tangent to innermost points of lobes). The auxiliary joining part diameter is set between these two reference diameters, creating an optimal interference fit that compensates for centering variations and ensures reliable anchoring despite manufacturing tolerances.
2Reliability
If the auxiliary joining part is pressed into the workpiece with high force to improve anchoring, then anchoring security increases, but the risk of damaging the workpiece or auxiliary joining part increases
Solution Approach 1:
The polylobular aperture creates an asymmetric contact pattern that distributes the pressing force across multiple lobes rather than concentrating it at a single point or along a single line. This distributed force application reduces peak stresses on both the workpiece and auxiliary joining part while maintaining sufficient friction and mechanical interlocking for secure anchoring.
Solution Approach 2:
By setting the auxiliary joining part diameter between the inscribed and circumscribed circle diameters of the polylobular aperture, the patent creates an optimal interference fit. This parameter relationship ensures adequate contact pressure for anchoring security while avoiding excessive forces that could cause damage to the workpiece or the auxiliary joining part itself.
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 configuration ensures secure anchoring of the auxiliary joining part in the workpiece, even with center offsets, by increasing the overlapping area between the die and the auxiliary joining part, thereby enhancing process reliability in series manufacturing.
Implementation Method 1
When the auxiliary joining part is being pressed in, the projections deform certain portions of the punching edge of the auxiliary joining part. This forms an undercut between the auxiliary joining part and the workpiece.
Data Source
AI summary
A device for inserting an auxiliary joining part into a workpiece, having a punch pressing the joining part into a top of the workpiece. The joining part has a shaft pressed into the workpiece and a die contacting a bottom of the workpiece while the joining part is pressed in. The die has a contact region and non-circular aperture surrounded thereby. Radially outermost points of the aperture periphery lie on an imaginary circumscribed circle, and radially innermost points lie on an imaginary inscribed circle. The aperture periphery includes three projections protruding into and touching the circumscribed circle. A diameter of the inscribed circle is between 4% and 10% smaller than a maximum diameter of a circular circumference of the auxiliary joining part, and a diameter of the circumscribed circle is between 2% and 5% larger than this diameter.