Piercing Nut Clinching for Stacked Plates Without Workpiece Breakage
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Solution Overview
Problem
Conventional methods for fastening a piercing nut to stacked plate-shaped workpieces result in insufficient extension of the peripheral portion into the annular groove, leading to reduced fastening force, and excessive force can cause deformation or breakage of the thinner workpieces.
Innovation Solution
A two-step clinching method involving a first clinching step where a clinching die with a truncated cone distal end is used to punch and extend the first plate-shaped workpiece, followed by a second clinching step with a clinching die having a smaller distal end diameter and reduced inclination angle to punch and extend the second plate-shaped workpiece on the outer portion of the first, ensuring deep penetration and smooth extension within the piercing nut's circumferential cavity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the clinching die is strongly driven to increase the fastening force between the outer plate-shaped workpiece and the piercing nut, then the fastening force is improved, but the part deformed by the extension is bent or broken
Solution Approach 1:
The fastening process is divided into two distinct stages: a first clinching step that creates initial extension of the outer workpiece, and a second clinching step that provides additional fastening force. This segmentation allows the deformation to occur in controlled increments rather than a single aggressive action, preventing workpiece failure while achieving sufficient fastening strength.
Solution Approach 2:
The first clinching step performs a preliminary extension of the outer plate-shaped workpiece into the annular groove, creating a base level of fastening. This preliminary action prepares the workpiece and groove interface for the second clinching step, allowing the subsequent strong driving force to be applied safely without causing immediate failure.
2Ease of manufacture
If a conventional single-step clinching method is used, then the process is simple, but the peripheral portion of the punched part is not sufficiently extended inside the annular groove, reducing fastening force
Solution Approach 1:
The fastening process is divided into two distinct stages: a first clinching step that creates initial extension of the outer workpiece, and a second clinching step that provides additional fastening force. This segmentation allows the deformation to occur in controlled increments rather than a single aggressive action, preventing workpiece failure while achieving sufficient fastening strength.
Solution Approach 2:
The first clinching step performs a preliminary extension of the outer plate-shaped workpiece into the annular groove, creating a base level of fastening. This preliminary action prepares the workpiece and groove interface for the second clinching step, allowing the subsequent strong driving force to be applied safely without causing immediate failure.
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 enhances the fastening strength of the piercing nut to the stacked workpieces by preventing insufficient extension, deformation, or breakage, thereby achieving high idling torque and clinching force.
Implementation Method 1
driving a clinching die with a tubular distal end surface from another surface side of the first plate-shaped workpiece to punch out the first plate-shaped workpiece in a circular shape, and extending a peripheral area of the punched portion in the circumferential cavity of the piercing nut
Data Source
AI summary
Provided is a fastening method capable of fastening a piercing nut to a stacked body in which a plurality of plate-shaped workpieces are stacked so as to develop a high fastening strength. A fastening method of a piercing nut 1 includes: a first clinching step of fastening a piercing nut 1 to a first plate-shaped workpiece W1 by punching out the first plate-shaped workpiece W1 in a circular shape, and extending a peripheral area of the punched portion in a circumferential cavity 4 of the piercing nut 1; and a second clinching step of punching out a second plate-shaped workpiece W2 in a circular shape, and extending a peripheral area of the punched portion on an outside of an extended portion W1f of the first plate-shaped workpiece W1 in the circumferential cavity 4 of the piercing nut 1.