Thread-Forming Fastener Insertion to Prevent Bulge Tearing
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Solution Overview
Problem
Connecting elements with low ductility can result in defects or cracks due to bulge tearing or bursting during the connection process, particularly when forming threads in workpieces.
Innovation Solution
A method involving controlled rotational speed and axial force variations is applied, with lower rotational speed and higher axial force in the initial stage, followed by higher rotational speed and reduced axial force in subsequent stages, to heat and deform the workpiece, enhancing ductility and preventing bulge tearing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a thread-forming connecting element is inserted by rotating it while in contact with the workpiece, then a thread is formed in the workpiece, but the workpiece is heated and the connecting element and workpiece experience friction and deformation
Solution Approach 1:
The patent applies parameter changes by varying the rotational speed and axial force during different stages of the connecting element insertion process. The rotational speed is adjusted from a first rotational speed to a second rotational speed, and the axial force is adjusted from a first axial force to a second axial force, optimizing both thread formation and heat generation control
2Productivity
If the connecting element is rotated at high speed to form a thread quickly, then productivity is improved, but the workpiece heating increases and may cause defects or cracks
Solution Approach 1:
The patent applies dynamics by making the rotational speed and axial force variable during the insertion process. The system transitions from a first rotational speed and first axial force to a second rotational speed and second axial force, allowing optimization of both productivity and workpiece integrity at different stages of the process
Solution Approach 2:
The patent applies periodic action by dividing the insertion process into distinct time periods with different rotational speeds and axial forces. The process alternates between higher speed/lower force phases and lower speed/higher force phases, optimizing both productivity and reliability through controlled periodic variations
3Strength
If the connecting element penetrates deeply into the workpiece to ensure secure connection, then connection strength is improved, but the non-pierced surface may experience bulge tearing or bursting
Solution Approach 1:
The patent applies parameter changes by adjusting the axial force and rotational speed during different stages of penetration. By varying these parameters, the process optimizes the balance between achieving sufficient connection strength and controlling the deformation of the non-pierced surface to prevent bulge tearing
Solution Approach 2:
The patent applies dynamics by making the insertion process adaptive, where the rotational speed and axial force are adjusted based on the penetration depth and material response. This dynamic control prevents excessive deformation and bulge tearing while ensuring secure connection
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 approach reduces or avoids defects by increasing the workpiece's ductility through controlled heating and penetration, ensuring a secure connection without bulge tearing or bursting.
Implementation Method 1
the fastening element is rotated while it is in contact with the workpiece, with the result that the workpiece is heated
Data Source
AI summary
The invention relates to a method for connecting at least two elements by a connecting element. The method comprises the steps of: providing a first element, a second element and the connecting element; placing the connecting element on a surface of the first element; in a first time period, rotating the connecting element at a first rotational speed and exerting a first axial force on the connecting element in the direction of the surface of the first element; and in a second time period, rotating the connecting element at a second rotational speed and exerting a second axial force on the connecting element in the direction of the surface of the first element.